2006 New York Code - Execution By Agent In Real Property Transactions; Written Authorization Required.

 
    § 5-1111. Execution  by  agent  in real property transactions; written
  authorization required.    If  executed  by  an  agent,  any  agreement,
  promise,  undertaking,  assignment  or offer required by section 5-1103,
  5-1105, 5-1107 or 5-1109 to be in writing, which affects or  relates  to
  real   property   or  an  interest  therein  in  any  manner  stated  in
  subdivisions one or two of section 5-703 of this chapter, shall be  void
  unless such agent was thereunto authorized in writing.